#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
#define rep(i, a, b) for (int i = (a); i <= (b); i++)
#define per(i, a, b) for (int i = (a); i >= (b); i--)
#define endl '\n'
const int N = 2e5 + 5;

int n, m, k;

void solve() {
  cin >> n >> m >> k;
  if (n + k < m) {
    cout << fixed << setprecision(10) << 0.0;
    return;
  }
  if (m <= k) {
    cout << fixed << setprecision(10) << 1.0;
    return;
  }
  // catalan
  // 1 - c(n+m, n+k+1) / c(n+m, n);
  double ans = 1.0;
  rep(i, 0, k) ans = ans * (m - i) / (n + 1 + i);
  ans = 1.0 - ans;
  cout << fixed << setprecision(10) << ans;
  return;
}
int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  int t = 1;
  while (t--) solve();
  return 0;
}